Improved texture loading (#3315)

* rework loading around `Arc<Loaders>`

* use `Bytes` instead of splitting api

* remove unwraps in `texture_handle`

* make `FileLoader` optional under `file` feature

* hide http load error stack trace from UI

* implement image fit

* support more image sources

* center spinner if we know size ahead of time

* allocate final size for spinner

* improve image format guessing

* remove `ui.image`, `Image`, add `RawImage`

* deprecate `RetainedImage`

* `image2` -> `image`

* add viewer example

* update `examples/image` + remove `svg` and `download_image` exapmles

* fix lints and tests

* fix doc link

* add image controls to `images` example

* add more `From` str-like types

* add api to forget all images

* fix max size

* do not scale original size unless necessary

* fix doc link

* add more docs for `Image` and `RawImage`

* make paint_at `pub`

* update `ImageButton` to use new `Image` API

* fix double rendering

* `SizeHint::Original` -> `Scale` + remove `Option` wrapper

* Update crates/egui/src/load.rs

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

* remove special `None` value for `forget`

* Update crates/egui/src/load.rs

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

* add more examples to `ui.image` + add `include_image` macro

* Update crates/egui/src/ui.rs

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

* update `menu_image_button` to use `ImageSource`

* `OrderedFloat::get` -> `into_inner`

* derive `Eq` on `SizedTexture`

* add `id` to loaders + `is_installed` check

* move `images` to demo + simplify `images` example

* log trace when installing loaders

* fix lint

* fix doc link

* add more documentation

* more `egui_extras::loaders` docs

* Update examples/images/src/main.rs

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

* update `images` example screenshots + readme

* remove unused `rfd` from `images` example

* Update crates/egui_extras/src/loaders/ehttp_loader.rs

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

* add `must_use` on `Image` and `RawImage`

* document `loaders::install` multiple call safety

* Update crates/egui_extras/Cargo.toml

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

* reshuffle `is_loader_installed`

* make `include_image` produce `ImageSource` + update docs

* update `include_image` docs

* remove `None` mentions from loader `forget`

* inline `From` texture id + size for `SizedTexture`

* add warning about statically known path

* change image load error + use in image button

* add `.size()` to `Image`

* Update crates/egui_demo_app/Cargo.toml

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

* add explanations to image viewer ui

---------

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

crates/egui_demo_lib/src/color_test.rs

@@ -87,8 +87,12 @@ impl ColorTest {
                 let tex = self.tex_mngr.get(ui.ctx(), &g);
                 let texel_offset = 0.5 / (g.0.len() as f32);
                 let uv = Rect::from_min_max(pos2(texel_offset, 0.0), pos2(1.0 - texel_offset, 1.0));
-                ui.add(Image::new(tex, GRADIENT_SIZE).tint(vertex_color).uv(uv))
-                    .on_hover_text(format!("A texture that is {} texels wide", g.0.len()));
+                ui.add(
+                    RawImage::new((tex.id(), GRADIENT_SIZE))
+                        .tint(vertex_color)
+                        .uv(uv),
+                )
+                .on_hover_text(format!("A texture that is {} texels wide", g.0.len()));
                 ui.label("GPU result");
             });
         });
@@ -225,11 +229,15 @@ impl ColorTest {
             let tex = self.tex_mngr.get(ui.ctx(), gradient);
             let texel_offset = 0.5 / (gradient.0.len() as f32);
             let uv = Rect::from_min_max(pos2(texel_offset, 0.0), pos2(1.0 - texel_offset, 1.0));
-            ui.add(Image::new(tex, GRADIENT_SIZE).bg_fill(bg_fill).uv(uv))
-                .on_hover_text(format!(
-                    "A texture that is {} texels wide",
-                    gradient.0.len()
-                ));
+            ui.add(
+                RawImage::new((tex.id(), GRADIENT_SIZE))
+                    .bg_fill(bg_fill)
+                    .uv(uv),
+            )
+            .on_hover_text(format!(
+                "A texture that is {} texels wide",
+                gradient.0.len()
+            ));
             ui.label(label);
         });
     }

crates/egui_demo_lib/src/demo/widget_gallery.rs

@@ -209,11 +209,14 @@ impl WidgetGallery {
         let img_size = 16.0 * texture.size_vec2() / texture.size_vec2().y;
 
         ui.add(doc_link_label("Image", "Image"));
-        ui.image(texture, img_size);
+        ui.raw_image((texture.id(), img_size));
         ui.end_row();
 
         ui.add(doc_link_label("ImageButton", "ImageButton"));
-        if ui.add(egui::ImageButton::new(texture, img_size)).clicked() {
+        if ui
+            .add(egui::ImageButton::new((texture.id(), img_size)))
+            .clicked()
+        {
             *boolean = !*boolean;
         }
         ui.end_row();